'\" et
.TH ISCNTRL "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.

.SH NAME
iscntrl,
iscntrl_l
\(em test for a control character
.SH SYNOPSIS
.LP
.nf
#include <ctype.h>
.P
int iscntrl(int \fIc\fP);
int iscntrl_l(int \fIc\fP, locale_t \fIlocale\fP);
.fi
.SH DESCRIPTION
For
\fIiscntrl\fR():
The functionality described on this reference page is aligned with the
ISO\ C standard. Any conflict between the requirements described here and the
ISO\ C standard is unintentional. This volume of POSIX.1\(hy2008 defers to the ISO\ C standard.
.P
The
\fIiscntrl\fR()
and
\fIiscntrl_l\fR()
functions shall test whether
.IR c
is a character of class
.BR cntrl
in the current locale,
or in the locale represented by
.IR locale ,
respectively; see the Base Definitions volume of POSIX.1\(hy2008,
.IR "Chapter 7" ", " "Locale".
.P
The
.IR c
argument is a type
.BR int ,
the value of which the application shall ensure is a character
representable as an
.BR "unsigned char"
or equal to the value of the macro EOF. If the argument has any other
value, the behavior is undefined.
.P
The behavior is undefined if the
.IR locale
argument to
\fIiscntrl_l\fR()
is the special locale object LC_GLOBAL_LOCALE or is not a valid locale
object handle.
.SH "RETURN VALUE"
The
\fIiscntrl\fR()
and
\fIiscntrl_l\fR()
functions shall return non-zero if
.IR c
is a control character; otherwise, they shall return 0.
.SH ERRORS
No errors are defined.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
To ensure applications portability, especially across natural
languages, only these functions and the functions in the reference pages
listed in the SEE ALSO section should be used for character classification.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIisalnum\fR\^(\|)",
.IR "\fIisalpha\fR\^(\|)",
.IR "\fIisblank\fR\^(\|)",
.IR "\fIisdigit\fR\^(\|)",
.IR "\fIisgraph\fR\^(\|)",
.IR "\fIislower\fR\^(\|)",
.IR "\fIisprint\fR\^(\|)",
.IR "\fIispunct\fR\^(\|)",
.IR "\fIisspace\fR\^(\|)",
.IR "\fIisupper\fR\^(\|)",
.IR "\fIisxdigit\fR\^(\|)",
.IR "\fIsetlocale\fR\^(\|)",
.IR "\fIuselocale\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2008,
.IR "Chapter 7" ", " "Locale",
.IR "\fB<ctype.h>\fP",
.IR "\fB<locale.h>\fP"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.unix.org/online.html .

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